A process for the preparation of self-crosslinking cationic paint binders which can be diluted with water after protonation and are obtained by reaction of an aminoalkylation product, containing secondary amino groups, of a phenol with a semi-blocked diisocyanate and subsequent reaction of the phenolic hydroxyl groups with epoxide compounds is disclosed in EP-B1-0 209 857. The products described can be used to formulate paints, the films of which, after stoving, have excellent corrosion-protection properties such as are required, for example, by the automobile industry. However, because of the reaction procedure, the process does not allow for the use of blocking agents for isocyanate groups which can be split-off at a temperature of below 140.degree. C. The temperatures of at least 95.degree. C. required in the aforesaid process for the reaction of the epoxide compounds with the phenolic hydroxyl groups leads to uncontrollable reactions, which may cause gelling of the reaction charge, when such blocking agents are used. Paints based on the binders according to EP-B1-0 209 857 thus require stoving temperatures above 150.degree. C., preferably of 160.degree. C. or more, in order to achieve the required film properties. Moreover, relatively highly viscous products are obtained by the disclosed process, which on the one hand necessitates the simultaneous use of relatively large amounts of organic auxiliary solvents, and on the other hand makes deposition of relatively high coating thicknesses difficult in an electrocoating process.